1. Field of the Invention
The present invention relates to medical retrieval or electro-cutting devices, and more particularly to a medical retrieval or electro-cutting device including a rotatable end effector.
2. State of the Art
Medical retrieval or electro-cutting devices are used for a number of purposes within the body cavity. For example, a medical retrieval device in the form of a snare instrument is used for the endoscopic removal of hypertrophic tissue growths or polyps within a body cavity. Snare instruments generally include an elongated tubular member, such as a catheter sheath, a wire or shaft extending through the tubular member, and an elastic wire (e.g., stainless steel or Nitinol) forming a loop movable distally and proximally within the tubular member. The loop can be opened by moving the loop beyond the distal end of the tubular member and closed by retraction into the tubular member. Loop opening and closing is effected by movement of the shaft relative to the tubular member. A handle is provided at the proximal end of the instrument to facilitate this movement.
With the loop of the snare instrument in a retracted position, the distal end of the instrument is inserted through an endoscope into the gastrointestinal tract and moved toward a polyp or other tissue growth which is identified for removal from the wall of the tract. The handle of the instrument is then operated to expand the loop of the snare and an attempt is made to maneuver the loop to surround the polyp. If successful, the loop is then constricted about the polyp to excise it.
It will be appreciated that manipulation of the loop of the snare instrument about the polyp is a difficult, and sometimes unattainable, task. The expanded snare loop often lies in a plane which is not conducive for maneuvering about the target polyp. Therefore, the desired polyp retrieval often requires extensive effort, including attempts to rotate the catheter sheath to orientate the snare loop about the polyp. Rotation of the catheter sheath, however, often moves the snare loop out of position or causes detrimental whipping of the snare loop during the procedure.